The Met Office said that a "tropical night" broke the United Kingdom's May heat record on Monday, May 27, 2024 [1].
This event marks a significant shift in seasonal temperature patterns, as the overnight minimum remained above the threshold typically associated with tropical climates. The persistence of high temperatures during the night prevents the environment and urban areas from cooling, which can exacerbate the effects of a heatwave.
At Kenley Airfield in London, the overnight minimum temperature did not fall below 21.3 °C (70 °F) [1]. This figure surpasses previous May night records set in 1922 and 1944 [2]. A "tropical night" is defined by the overnight minimum temperature staying above 20 °C [1].
Concurrent with the overnight record, the UK also recorded a new daytime high for May. Kew Gardens in south-west London reached 34.8 °C [3]. This surge in temperature is attributed to a heatwave pushing temperatures high enough to sustain record-breaking levels across both day and night cycles [1].
The Met Office said that temperatures could continue to climb, noting that 35 °C is possible on Tuesday [2]. The concentration of these records in the London area highlights the intensity of the current heat event, a phenomenon that often sees amplified temperatures in urban centers due to the heat island effect.
Meteorologists continue to monitor the system as it moves across the region. The combination of a record-breaking daytime peak and a historic overnight minimum creates a rare meteorological profile for the month of May in the UK [1].
“A 'tropical night' broke the UK May heat record.”
The occurrence of a 'tropical night' in the UK indicates a rare failure of the overnight cooling process during the spring. When minimum temperatures remain above 20 °C, it suggests a high atmospheric heat load that can increase health risks for vulnerable populations and put additional stress on infrastructure not designed for sustained tropical heat.
